Fuel-operated heaters are used as parking heaters or auxiliary heaters for supplying heat in motor vehicles. A mixture of fuel and combustion air is ignited and burnt in these. The heat generated in the process is transmitted to a heat carrier medium, for example, the air to be introduced into an interior chamber of the vehicle or to the cooling agent circulating in an engine coolant system. Catalytic burners (catalytic combustion (reaction) devices) are known to be used in order to make it possible to meet the ever-increasing requirements imposed in terms of pollutant emission, especially also during the start-up phase of combustion. The combustion of fuel and combustion air is achieved in these by a process supported catalytically on the surface of catalytic material.
Such a catalytic burner is known from WO 2007/003649 A1. The fuel fed through a fuel feed line in the form of droplets is introduced in this catalytic burner into a pot-like evaporator. This evaporator is open opposite the direction of flow of the combustion air being fed with the fuel for combustion. The combustion air flowing into the pot-like evaporator leads to swirling in the interior of this pot-like (pot shaped) evaporator, and this swirling leads to thorough mixing of the combustion air with the fuel accumulating therein. The mixture thus formed from combustion air and fuel leaves the pot-like evaporator via an edge area of a circumferential wall of said pot-like evaporator and then reaches further to a combustion chamber, in which the catalyzer device with a plurality of catalyzer units, which follow each other in the direction of flow and through which the fuel/combustion air mixture can flow, for the combustion of this fuel/combustion air mixture.